Based on Rickeyship's feedback, I'm changing my answer.

Environmental Context

The answer depends on your environment, so try to find out what makes sense in the context of where you'll be. My original answer works well in the woods of Missouri where your droppings will be subsumed into the environment, and you can make your catholes undetectable. However, if you're in a fragile environment, or an environment where droppings take longer to process, that approach would be problematic. Ricketyship gives the case of the western ghats as one such example. The arctic might be another, if I were to guess.

In the fragile environments, follow his advice of a single, larger cathole.

But overall, I think the right approach is to know the environment you're entering, and determine what the right answer would be in that particular context.

Original answer

Your cathole shouldn't leave a trace - that is, shouldn't be visible to anyone after use. So in that regard, maybe work on making your covered catholes invisible.

When I use them, and when I've read about them, they're always small and only big enough for one use.

Properly made, closed catholes shouldn't attract animals. Open ones might, but I've never left a used one open. One thing I've done that was helpful was to dig one before gong to bed so that I can use it first thing in the morning without need time to locate and dig one.

Also, a cathole shouldn't damage the environment. So, save the top layer, whether grass or sticks and leaves, and put it back. Your droppings and toilet paper are fertilizer, and will become part of the earth quickly, benefitting the environment.